86954-34-9Relevant articles and documents
Reaction of Np(VI) with H2O2 in carbonate solutions
Shilov,Fedoseev
, p. 245 - 249 (2010)
The kinetics and stoichiometry of the reaction of Np(VI) with H 2O2 in carbonate solutions were studied by spectrophotometry. In the range 1-0.02 M Na2CO3, the reaction 2Np(VI) + H2O2 = 2Np(V) + O2 occurs, as δ[Np(VI)]/δ[H2O2] ≈ 2. In Na 2CO3 + NaHCO3 solutions, the stoichiometric coefficient decreases, which is caused by side reactions. The reduction at low (1 mM) concentrations of Np(VI) and H2O2 follows the first-order rate law with respect to Np(VI), which suggests the formation of a Np(VI) peroxide-carbonate complex, followed by intramolecular charge transfer. Addition of Np(V) in advance decreases the reaction rate. An increase in the H2O2 concentration leads to the reaction deceleration owing to formation of a complex with two peroxy groups. In a 1 M Na 2CO3 solution containing 1 mM H2O2, the first-order rate constant k increases with a decrease in [Np(VI)] from 2 to 0.1 mM. For solutions with [Np(VI)] = [H2O2] = 1 mM, k passes through a minimum at [Na2CO3] = 0.5-0.1 M. The activation energy in a 0.5 M Na2CO3 solution is 48 kJ mol-1. Pleiades Publishing, Inc., 2010.
Reduction of Np(VI) with Hexamethylenetetraacetic Acid in HClO4 Solution
Fedoseev, A. M.,Shilov, V. P.
, p. 170 - 172 (2020)
Abstract: Spectroscopic method was used to examine the stoichiometry of the reaction of No(VI) with hexamethylenediaminetetraacetic acid (HMDTA, H4hmdta) in a 0.05 M HClO4 solution. At an excess of Np(VI), 1 mole of complexon reduces about 4 moles of Np(VI) to Np(V). In 0.1–1.0 M HClO4 solutions (the ionic strength of 1.0 was maintained with LiClO4) containing 2–20 mM HMDTA, neptunium(VI) with concentration of 0.3–3.0 M decreases at 35–55°C by the first-order rate law until the instant when less than 20% Np(VI) remains. The initial reaction rate has the first order in [HMDTA] and –2 order in [H+]. An activated complex is formed with loss of two H+ ions. The activation energy is 102 ± 7 kJ/mol.
Catalytic reduction of Np(VI) with formic acid in the presence of platinum nanoparticles
Anan'ev,Shilov,Sukhov,Abkhalimov,Ershov
, p. 125 - 132 (2006)
The kinetics of catalytic reduction of Np(VI) with formic acid in the presence of Pt nanoparticles of different types ( brown colloid stabilized with sodium polyacrylate and nonstabilized gray colloid) was studied. In both cases in the examined range of conditions ([Np(VI)] 0 = 2.80 × 10-4-9.03 × 10-4 M; [HCOOH] = 0.03-1.0 M; [Pt] = 4 × 10-7-2 × 10-5 M; T = 18-60°C) the reaction is zero-order with respect to [Np(VI)] and first-order with respect to [HCOOH]. The catalytic activity of the nonstabilized gray colloid exceeds by almost an order of magnitude that of the brown colloid, due to the blocking effect of stabilizing polyelectrolyte molecules on the active catalytic centers. The dependence of the reaction rate on the sodium polyacrylate concentration in the range 1 × 10-4-1 × 10-2 M is nonmonotonic, due to deflocculation of the nanoparticles. The mechanism of the catalytic reduction of Np(VI) with formic acid in the presence of Pt colloids is discussed; it involves a slow step of dissociative chemisorption of HCOOH molecules on the nanoparticle surface. Pleiades Publishing, Inc., 2006.
Kinetics and mechanism of Np(IV) oxidation with nitric acid
Koltunov,Taylor,Marchenko,Savilova,Dvoeglazov,Zhuravleva
, p. 252 - 257 (2005)
Neptunium (IV) is oxidized to Np(V) with nitric acid in the presence of U(VI) under conditions of low acidity (1[Np(IV)]/[H +]2 + k 2[Np(I
